It depends on what your UI is. If your page displays information that can be loaded with a few concurrent calls to a single RESTful endpoint each, then by all means stick with that.

On the other hand, if your page loads information from ten different endpoints across three different services, and some calls depend on the results of previous calls, then you have four options: take a massive performance hit, go back to rendering everything on the server, create an endpoint for each page, or implement some way of querying embedded resources.

GraphQL acting as an intermediary for multiple REST apis is one way of doing the latter.